Question

A block of mass m is kept on another block of mass M. Initially they are kept at rest. Now upper block is pulled by a force F. Find maximum value of F so that blocks move together (m = 4 kg, M = 6 kg, $\mu$ = 0.6)

• A. 30 N
• B. 10 N
• C. 20 N
• D. 40 N

Answer 1

The correct option is D 40 N


Let common acceleration be "a"
$a=\frac{F}{m+M}=\frac{f}{M}$
$f=\left(\frac{F}{m+M}\right)M=\frac{6F}{10}\le 0.6\times 40$
$F<40$ N